Propeller



Afiril 5 1927. 1,623,420

w. H. LEmwgBsR rnorsmlsn Fil'ed June 27. 1925 y I -IN\VENTOR.

WILLIAM H. LEINWEZBER K ATTORNEY.

Patented Apr. 5, 1927.

UNITED STATES PATENT OFFICE.

wILLInt n. mntwnnnn, or care aeo, rumors, assrenoa or ONE-THIRD '10vrc'roa H. Lamar-2a AND ONE-THIRD roctm'rrs n. nnmwnnnn, Bornor-ncnrcaeo,

ILLINOIS.

raornnnna,

Application filed June 27, 1925, Serial No. 89,957, and in CanadaJanuary 26, 1924.

My invention relates to propellers used for setting in motion fluidwhether liquid or gaseous by rotation of the propeller and for moving if'desired, the structure sup- 5 porting the propeller relatively to thefluid instead of maintaining the said structure stationary and producingmotion of the fluid only. In other words my improved propell'er-1sadaptedlfor any purpose for which 9 fans and propellers may be used,whether for producin currents of air or other gases for ventilating andcirculating purposes, currents for water circulatin urposes, motion ofair craft, or motion oats.

Y My invention is characterized by animroved construction of thesurfaces engagmg the fluid, in'such a manner that at any. part of theoperating surface of the fan, the ,surface at its edge entering thefluid is in a 0 plane through the entering edge at subst 'tially rightangles to the axis'of the propeller' shaft, from which entering edge theoperating surface is displaced progressively across the -operatinsurface towards the 5 trailing ed of the b ade in the direction ofthrust on t e fluid in such a manner that for equal increments acrossthe surface angularly, the displacement increases at a greater rate thanproportionally 9 travel across the operating surface, or -in other wordsthe operating surface at any radius of the fan blade is a curve, whichpreferably imparts uniform acceleration to the fluid. from the enteringedge to the trailing 5 edge of the blade, assuming that the propelher isheld against axial motion, or theoretically, assuming the fluid to benon-yielding, that would produce uniform acceleration during the sameinterval of the supporting 0 structure and fan if the latter weremovable axially of the propeller. More specifically, the curvature ofthe blade extending laterally of the propeller is such that eachincrement of angular travel at any radius across said operating surface,im arts an increment'of velocity to the flui assuming the propeller tobe held against axial mo-.

tion, these increments being so related that to the angular eachincrement of velocity, for equal increments of travel across theoperating surface so at sa1d radius of the blade, is equal to each otherincrement of velocity. In this .man-

ner the'inertia of the mass set in motion axially of the propeller byits rotation,

whether it be the mass of the fluid or'the 65 v mass of the s'upp'ortinstructure of the pro- =--peller, is: overcome wit -.maximum efliciency.

The particular curvature given the operating surface of the blade isdetermined by the maximum displacement axially of the propeller', whichis desired at that particular radius of the propeller. blade and isexpressed by theformulagiven below. The sharpness of curvature of theoperating surface at any radius and for any desired displacement at thatradius, is determined by the width of the operating surface of the bladeat that radius, this curvature being less sharp for a wide blade than itis for a narrow blade under these conditions A further feature of myinvention consists in proportioning the operating surface of thepropeller to distribute the thrusts upon .it uniformly over said surfaceradially of the propeller. This I accomplish by changing the maximumdisplacement of the op- I eratin surface of the bladeaxially of the -proe er, so that it progressively decreases as t e radius of the operatingsurface increases the maximum axial displacements at difl'erentradiibeing inversely proportional to the radii. In this manner I'producea large displacement near the axis of the propeller where the linealtravel of the operating surface angularly is small and a smalldisplacement of the operating surface at the outer end of. thebladewhere the lineal travel of the operating surface is great, therelation preferably being such that the prodnot of sa1d lineal travel atany radius, by the maximum displacement axially of the operating surfaceat that radius of the blade,

is equal to the similar product for any'other radius of the blade. Inthis'manner each radial increment of operating surface produces 96 thesame amount of thrust as each other ra-' gpeller consisting of twoblades nor to a prodial increment and the thrust produced by the bladeis uniformly distributed over its surface radially. A result of thecurved distribution of thrust radially but also laterally thereof, or 1nother words conformation laterally of the operating surface of theblade, above described, is thatthe thrust produced-by any ra'dialincrement of operating surface '18 uniformly distributed over saidincrement laterally of the blade. In-this manner I produce not onlyuniform of the blade I each unit of the operating surface of the bladehas exerted upon it the same pressure.

as each other unit of said operating surface- .My invention will best beunderstood by.

reference to' the accompanying drawings showlng one form in which mymventlon ma be embodled, sa d draw ngs belng as.

fol ows: Fig. 1 shows a propeller. 1n accordance with my invention, 1nside elevatlon,

.Fig. 2 shows the propeller illustrated in Fig. 1,- in front elevation,and.

I Fig. 3.is a sectional view showing a plurahty of sections ai inclusivetaken along corresponding lines through one of the blades of thepropeller shown in Fig. 2.

@Similar numerals refer 'to similar parts a I throughout the severalviews. 0.

- -As shown in the drawings, my propeller consists of a hub having acentral bore 11 to receive a supporting shaft, from which 1 hub oppositeblades 12, .12 extend radially.-

The propeller may be-made of any desiredmaterial for ,example wood or.metal depend i'ng upon the purpose for which it is to be )used and ifmade of metal it may be made 5in any desired manner adapted for theintended purpose. It will further be understood that I do not limitmyself to a pro- ,p ell'er having any particular size or proportion ofblades; the number of blades em.

w-p'loyed, and the particular size, shape and proportion of the bladesmay be determined .;1n any case according to the re uiremcnts of thatcase and the particular uid to be engaged by the .operatlngsurfaces. ofthe blades. The essential feature "of my inven tion is that theoperating. surface ,-of each blade shallbe shaped to realize theimproved operation' "characterizing my invention. To

secure this result each of the blades for' example the upper bladeshown'in; Fig. 2,

is provided with an operating surface hav- 4 ing a curvature of thenature generally described above, forexamplethat illustrated by theseveral sections of said" blade shown in Fig. 3, said sections beingtaken at the correspondingly lettered lines in Fig. 2, that. is to saysection ais' adjacent the outcr'end of the blade, section b is taken-somewhat nearer the axis of the propeller and soon, section i bemgtakennear the hub 10 of the propeller. In each of the sectionalviews shown inFig. 3, the right hand edge of the section is the entering edge of theblade into the fluid to be acted upon, said entering edge beingdesignated a 6 2' for the sections, a, b, 13 respectively. The curvatureof the operating surface of the blade laterally thereof at each sectionis determined as follows: the light horizontal lines through the edges(1 b 5 are each in the planeaof rotation of the corresponding enteringedge, that is to say in a plane at right angles to the axis of thepropeller. lines are through the entering and trailing edges of theblade at the correspondinglse'ction; the distance apart of theentering-and trailing edges for each section is designated In eachsection, the light vertical by :0 and the axial displacement of thetrail- 5 ing edge from the plane'of rotation through-'. the enteringedge for any; section is desig-f hated by y.

The curvature of. the operating surface oftheObIade laterally at anyradius of the blade, :for example at section i,'is such'that forequalincrements of the abscissam lat ierally, of the operating surface,relatively to thepoint i as a reference point or origin,

the ordinateor :1; [value of the curve shall" PIOgI'GSSIVGly increase bysuccesslvely-greater increments each "than the preceding- 1n amanner tocontinuously accelerate fluid enigaged by the operating surface,assuming the" propeller to be held against axial displacement. I have.found? that this curve" maybe expressed by the formula of the bladeforany particular .widthof operating surface. *In practice I find itadvisable and desirable to maintain the fac-- tors f for the differentradii of the operat ing surface of any bladeinversely proportional' tosaid radii, that is to say the-value ofthe factor f at the extremeouter'- end of the operating surfaceshould be halftbe value of the saidfactor at .a point on the operating surface .half Way from the axis ofthe'propeller to the outermost radius of tlIepPerating surface and so onfor the o crat ng surface at other radii. j, lt will be 0 served thatthe nature. of the-f jiiurve the same for any value of the factor 7whether the curve is relatively flat or relatively abrupt beingexpressed in each case by theexpression In using this formula, todetermine the value v of the factor f for the curvature. of the bladeamount of thrust it is desired to produce in view of the fluid actedupon and the speed at which the propeller is to be driven. These valuesgive the maximum values of a: and y which are substituted in the formulaand the value of f if then equal to 3 divided by The value of the factorf being determined for this particular radius, its'values for otherradii are determined by the inversely proportional'relation abovereferred to.

As a result of the construction described, the operating surface has acurvature .at any particular radius which uniformly accelerates' fluidset in motion by it moving across said 0 crating surface for uniformrotation of t e propeller blade, assuming the propeller to be heldagainst axial motion, and further provides that this uniformacceleration shall be the same across'the operating surface at anyradius; The above for- .mula applies to propeller blades whether theyareof uniform width or tapered longi- 1 tudinally, the only differencebeing thatin the first case the value of a: maximum is constant, whereasin the latter case it decreases in the direction of convergence of thewidth of the operating surface. From the above it will be observed thatthe operating surface for my improved propeller is curved bot-hlaterally and longitudinally, the former curvature imparting the uniformacceleration referred to and the latter curvature compensating forincreasing lineal travel of the operating surface from adjacent the hubof the propeller outwardly radially to the extreme outer end of theoperating surface and that in this manner each. unit surface of theoperating surface is subjected to the same thrust as each other unitsurface thereof.

' To engage the fluid with maximum efli ciency adjacent the hub '10,the-trailing edge I of the operating surface i. is continued towards theaxis of the propeller in the form of a smooth curve 13 tangent to thecircumference of the hub 10- forming a pocket 14 receiving the fluidadjacent 'the hub and acting upon it substantially as described for themajor portion of the operating surface, In this way undesirable eddycurrents and losses are prevented adjacent-the hub portion of thepropeller.

Each of the blades of any particular propcller is preferably providedwith the same kind of an operating surface determined as above set forthand the number of blades in any propeller, and the width of the bladesrelatively to the spaces between them, are

determined by principles well known in the art. applying to theparticular conditions involved In any particular case.

' The formula abovegiven for the lateral curvature of the propellerblades is equallyapplicable for fluid media of different de-.

grees of mobility as follows: Without modi-. ficatlon, the formula andits method of application described applies to fluids theoreticallyimmobile; from data well known in the art concerning any particularfluid, approximately the amount of slip due to mebility-of the fluidmaybe ascertained for the particular speed of operation contemplated;the factor of slip being determined and expressed as increaseddisplacement required, the factor f in the formula is multiplied by theslip factor and in this manner the degree of curvature laterally isaffected in a manner to compensate throughout its extent for the saidslip The resulting factor' fi then becomes the basis for determin- 1ingthe similar factors at other radii of the operating surfaces of thepropeller blades. In a similar manner any other practical conditiondeparting from theoretical operation, maybe compensated for.

' While I have shown m invention in the particular embodiment a o've'described,'it will be understood that I do not limit myself to thisexact construction, but that I may employ, equivalents known to the art.at the time of the filing of this application without departing from thescope ofthe appended claims.

What I claim, is: 1. -A propeller having a ating surfaces, eachcurved-laterally with axial displacements increasing progressivelymorerapidly than proportional to'the traverse of said surface from itsentering edge to its trailing edge, the plane of the entering edge ofeach of said surfaces being substantially perpendicular 'to the axis ofthe, propeller, and'each of said surfaces being curved radially of" thepropeller making the maximum axial displacements of said surface atdifferent radiisubstantially inversely proportional to said radii.

2.- A propeller having a' plurality of operating surfaces, each curvedlaterally with axial displacements increasing progressively more rapidlythan proportional to the trav-' erse of said surface from its enteringedge faces being-curvedradially of the propeller making the maximumaxialydisplacements of said surface 'at' different'radii substantiallyinversely proportionalto said radii.

to its trailing edge, and'e'ach of said; sur' n tially proportlonal tothe forum 5 ating surfaces, each curved laterally from its entering edgeto its tr g edgi e substan- 'where y is the axial displacement of saidsurface at any point from the plane of rotation ofits enterin edge and mis the lateral distance of =sai point from said entering ed and havingaxial dis lacements at its tra g ed substantially inversely proportionalto t e distances of said displacements from the pro er axis.

In witness whereof, I hereunto subscribe my name this 24th day of June,A. D. 1925.

WILLIAM LEINWEBER.

